Add basic macOS driver updater implementation

[JusterZhu]

Summary

Replace the pure-placeholder macOS updater with a working BaseDriverUpdater subclass.

Changes

MacOsGeneralDrivelution

• Now inherits BaseDriverUpdater (was throwing PlatformNotSupportedException on every method)
• InstallCoreAsync: .kext (kextload + kextcache), .dext (systemextensionsctl), .pkg (installer)
• RollbackAsync: restores backed-up kext files to /Library/Extensions/ and reloads via kextload
• Driver discovery: finds .kext, .dext, .pkg files, parses CFBundleVersion from Info.plist
• sudo check pipeline step

MacOSDriverValidator

• Hash validation: delegates to HashValidator (file I/O, works on all platforms)
• Signature validation: uses codesign tool with -v / --deep verification
• Compatibility: delegates to CompatibilityChecker

MacOSDriverBackup

• Pure .NET file copy/restore/delete (no macOS-specific APIs)
• Supports both file and directory (kext bundle) backup

Factory

• DrivelutionFactory.Create now returns a working MacOsGeneralDrivelution on macOS
• IsPlatformSupported() returns true for macOS

Limitations

• .kext requires SIP disabled on Apple Silicon (Apple deprecation)
• .dext requires user approval in System Preferences

Closes #294